528
528
Jun 14, 2010
06/10
by
jeff Carter
movies
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An animated wind farm during a rain shower
Topics: Wind Farm, Windmill, Turbine, Fan, Fan Blades, Blades, Spin, Spinning, Rain
180
180
Jul 12, 2010
07/10
by
Lutes, G. F
texts
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An optical fiber communications link was installed for the purpose of evaluating the applicability of optical fiber technology to the distribution of frequency and timing reference signals. It incorporated a 1.5km length of optical fiber cable containing two multimode optical fibers. The two fibers were welded together at one end of the cable to attain a path length of 3km. Preliminary measurements made on this link, including Allan variance and power spectral density of phase noise are...
Topics: NOISE MEASUREMENT, PROPELLER FANS, SHROUDED PROPELLERS, WIND TUNNEL TESTS, FAN BLADES, PERFORMANCE...
Frank Quinto, facility manager for the 14- by 22 Foot Subsonic Tunnel, inspects the fan blade area of the tunnel. Technicians erected scaffolding (in the background) to remove the blades for minor repairs. The fan blades will be re-installed so the tunnel can be up and running again by the end of the month. Credit: NASA/Sean Smith
Topic: wind tunnel, Frank Quinto, inspection, fan blades, 14 x 22 Wind Tunnel, 14 x 22
Source: http://www.nasa.gov/centers/langley/multimedia/iotw_14x22.html
Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan...
Topics: NASA Technical Reports Server (NTRS), CENTRIFUGAL FORCE, FAN BLADES, MECHANICAL ENGINEERING,...
This document provides a summary of the research conducted for the NASA Ames Research Center under grant NAG2-1182 (Condition-Based Monitoring of Large-Scale Facilities). The information includes copies of view graphs presented at NASA Ames in the final Workshop (held during December of 1998), as well as a copy of a technical report provided to the COTR (Dr. Anne Patterson-Hine) subsequent to the workshop. The material describes the experimental design, collection of data, and analysis results...
Topics: NASA Technical Reports Server (NTRS), DATA ACQUISITION, MULTISENSOR FUSION, EXPERIMENT DESIGN,...
As fan tip speeds are reduced, broadband noise is becoming more important in the calculation of perceived noise. Past experience indicates that lower vane number stators with either constant chord or constant solidity may be a way to reduce broadband noise caused by the interaction of the rotor wake turbulence with the stators. A baseline fan and a low blade number fan were investigated to determine if a noise reduction was possible. The low vane number fan showed a 2 PndB and a 1.5 PNLT noise...
Topics: NASA Technical Reports Server (NTRS), NOISE REDUCTION, FAN BLADES, STATORS, LOW SPEED, ROTORS,...
Modern turbofan engines employ a highly loaded fan stage with transonic or low-supersonic velocities in the blade-tip region. The fan blades are often prone to flutter at off-design conditions. Flutter is a highly undesirable and dangerous self-excited mode of blade oscillations that can result in high-cycle fatigue blade failure. The origins of blade flutter are not fully understood yet. The latest view is that the blade oscillations are triggered by high-frequency changes in the extent of the...
Topics: NASA Technical Reports Server (NTRS), AIRFOILS, FAN BLADES, FAILURE, BOUNDARY LAYER CONTROL, FLOW...
Complete tabulations of 1/3-octave band acoustic measurements are given.
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, NOISE SPECTRA, SPACING, VANES, GRAPHS (CHARTS),...
Scoping of shape changing airfoil concepts including both aerodynamic analysis and materials-related technology assessment effort was performed. Three general categories of potential components were considered-fan blades, booster and compressor blades, and stator airfoils. Based on perceived contributions to improving engine efficiency, the fan blade was chosen as the primary application for a more detailed assessment. A high-level aerodynamic assessment using a GE90-90B Block 4 engine cycle...
Topics: NASA Technical Reports Server (NTRS), AIRFOILS, COMPRESSOR BLADES, DESIGN ANALYSIS, FAN BLADES,...
Under a Space Act Agreement between the Kirby company and Lewis Research Center, NASA technology was applied to a commercial vacuum cleaner product line. Kirby engineers were interested in advanced operational concepts, such as particle flow behavior and vibration, critical factors to improve vacuum cleaner performance. An evaluation of the company 1994 home care system, the Kirby G4, led to the refinement of the new G5 and future models. Under the cooperative agreement, Kirby had access to...
Topics: NASA Technical Reports Server (NTRS), AIR FLOW, CLEANERS, COMPUTER PROGRAMS, FAN BLADES, NOZZLE...
A nonintrusive optical method for measurement of propeller blade deflections is described and evaluated. It does not depend on the reflectivity of the blade surface but only on its opaqueness. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained using a single light beam generated by a low-power helium-neon laser. Quantitative analyses are performed from taped signals on a digital computer. Averaging techniques...
Topics: NASA Technical Reports Server (NTRS), DEFLECTION, DISPLACEMENT MEASUREMENT, OPTICAL MEASUREMENT,...
148
148
Jun 1, 2011
06/11
by
Newman, Paul A.; Nash, Eric R
texts
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The southern hemisphere stratospheric winter of 2002 was the most unusual winter yet observed in the southern hemisphere climate record. Temperatures near the edge of the Antarctic polar vortex were considerably warmer than normal over the entire course of the winter. The polar night jet was considerably weaker than normal, and was displaced more poleward than has been observed in previous winters. These record high temperatures and weak jet resulted from a series of wave events that took place...
Topics: FAN BLADES, HYDRODYNAMICS, COMPUTERIZED SIMULATION, DYNAMIC LOADS, ROTOR BLADES (TURBOMACHINERY),...
At the NASA Glenn Research Center, we have been training artificial neural networks to interpret the characteristic patterns (see the leftmost image) generated from electronic holograms of vibrating structures. These patterns not only visualize the vibration properties of structures, but small changes in the patterns can indicate structural changes, cracking, or damage. Neural networks detect these small changes well. Our objective has been to adapt the neural-network, electronic-holography...
Topics: NASA Technical Reports Server (NTRS), VIBRATION, FAN BLADES, DAMAGE, DATA ACQUISITION, NEURAL NETS,...
377
377
Jun 13, 2011
06/11
by
Greene, Ben; McClure, Mark B.; Johnson, Harry T
texts
eye 377
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Selection of personal protective equipment (PPE) for hydrogen peroxide service is an important part of the hazard assessment process. But because drip testing of chemical protective clothing for hydrogen peroxide service has not been reported for about 40 years, it is of great interest to test new protective clothing materials with new, high-concentration hydrogen peroxide following similar procedures. The suitability of PPE for hydrogen peroxide service is in part determined by observations...
Topics: FAN BLADES, THICKNESS, SHEAR STRESS, VIBRATION, SANDWICH STRUCTURES, STAINLESS STEELS, COST...
In 1981, Glenn Research Center scientist Dr. Larry Viterna developed a model that predicted certain elements of wind turbine performance with far greater accuracy than previous methods. The model was met with derision from others in the wind energy industry, but years later, Viterna discovered it had become the most widely used method of its kind, enabling significant wind energy technologies-like the fixed pitch turbines produced by manufacturers like Aerostar Inc. of Westport,...
Topics: NASA Technical Reports Server (NTRS), ENERGY TECHNOLOGY, WINDPOWER UTILIZATION, CLIMATOLOGY, WIND...
All turbofan engines work on the same principle. A large fan at the front of the engine draws air in. A portion of the air enters the compressor, but a greater portion passes on the outside of the engine this is called bypass air. The air that enters the compressor then passes through several stages of rotating fan blades that compress the air more, and then it passes into the combustor. In the combustor, fuel is injected into the airstream, and the fuel-air mixture is ignited. The hot gasses...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, CASING, TURBOFAN ENGINES, DAMAGE ASSESSMENT, COST...
This final report has been prepared by Honeywell Aerospace, Phoenix, Arizona, a unit of Honeywell International, Inc., documenting work performed during the period September 2004 through November 2005 for the National Aeronautics and Space Administration (NASA) Glenn Research Center, Cleveland, Ohio, under the Revolutionary Aero-Space Engine Research (RASER) Program, Contract No. NAS3- 01136, Task Order 6, Noise Measurements of the VAIIPR Fan. The NASA Task Manager was Dr. Joe Grady, NASA Glenn...
Topics: NASA Technical Reports Server (NTRS), NOISE MEASUREMENT, AERODYNAMIC NOISE, UPSTREAM, FAN BLADES,...
455
455
Jun 1, 2011
06/11
by
Dorney, Daniel J.; Rothermel, Jeffr
texts
eye 455
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During a post-flight inspection of the liquid hydrogen feed lines leading the Space Shuttle main engines cracks were discover in slots on a flow liner just upstream of the low pressure fuel pump inducer. Numerical simulations have been performed for the feed line, the flow liner (including the slots and backing cavity) and the inducer. The predicted results have been compared with experimental data taken during hot-fire tests at NASA Stennis Space Center.
Topics: AERODYNAMIC NOISE, BYPASSES, FAN BLADES, NONUNIFORMITY, DUCTED FANS, NOISE PROPAGATION, RADIATION,...
The use and application of the COBSTRAN (COmposite Blade STRuctural ANalyzer) computer code is presented. COBSTRAN was developed at NASA-Lewis and is currently being used for the design and analysis of aircraft engine ducted and unducted fan blades. The features of COBSTRAN are demonstrated for the modeling and analysis of a scaled down wind tunnel model propfan blade made from fiber composites. Comparison of analytical and experimental mode shapes and frequencies are shown, verifying the model...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, FAN BLADES, FIBER COMPOSITES, STRUCTURAL...
With the advent of ultrahigh-bypass engines, the space available for passive acoustic treatment is becoming more limited, whereas noise regulations are becoming more stringent. Active noise control (ANC) holds promise as a solution to this problem. It uses secondary (added) noise sources to reduce or eliminate the offending noise radiation. The first active noise control test on the low-speed fan test bed was a General Electric Company system designed to control either the exhaust or inlet fan...
Topics: NASA Technical Reports Server (NTRS), ACTIVE CONTROL, AERODYNAMIC NOISE, FAN BLADES, AEROACOUSTICS,...
Research is underway to establish an increased level of confidence in existing numerical techniques for predicting transient behavior when the fan of a jet engine is released and impacts the fan containment system. To evaluate the predictive accuracy that can currently be obtained, researchers at the NASA Lewis Research Center used the DYNA 3D computer code to simulate large-scale subcomponent impact tests that were conducted at the University of Dayton Research Institute (UDRI) Impact Physics...
Topics: NASA Technical Reports Server (NTRS), CONTAINMENT, FAN BLADES, FINITE ELEMENT METHOD, IMPACT TESTS,...
Aircraft engine noise research in the United States has made considerable progress over the past 10 years for both subsonic and supersonic flight applications. The Advanced Subsonic Technology (AST) Noise Reduction Program started in 1994 and will be completed in 2001 without major changes to program plans and funding levels. As a result, significant progress has been made toward the goal of reducing engine source noise by 6 EPNdB (Effective Perceived Noise level in decibels). This paper will...
Topics: NASA Technical Reports Server (NTRS), JET AIRCRAFT NOISE, ENGINE NOISE, NOISE REDUCTION, RESEARCH,...
Version 1.4 of TFaNS, the Tone Fan Noise Design/Prediction System. has recently been evaluated at the NASA Glenn Research Center. Data from tests of the Allison Ultra High Bypass Fan (UHBF) were used to compare to predicted farfield directivities for the radial stator configuration. There was good agreement between measured and predicted directivities at low fan speeds when rotor effects were neglected in the TFaNS calculations. At higher fan speeds, TFaNS is shown to be useful in predicting...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, NOISE PREDICTION, AERODYNAMIC NOISE, BYPASSES,...
This paper describes further assessment of the CDUCT-LaRC code via comparison with static engine test data. In an effort to improve confidence in the use of CDUCT-LaRC for liner optimization studies addressing realistic three-dimensional geometries, inlet radiated fan noise predictions were performed at 54% and 87% engine speed settings. Predictions were then compared with far-field measurements to assess the approach and implementation. The particular configurations were chosen to exercise the...
Topics: NASA Technical Reports Server (NTRS), NOISE PREDICTION, AERODYNAMIC NOISE, FAN BLADES, ENGINE...
Developing design methodologies based on experimentally validated predictive numerical simulation methods will enhance existing capabilities in predicting failure modes and structural design optimization for the high velocity impact problems. This paper is thus concerned with the setup of a methodology for modeling and simulation of the containment problem for the case of a real hybrid metallic/soft layered composite fancase structure. To realize this new design, a debris protection fan case...
Topics: DTIC Archive, DEFENCE RESEARCH AND DEVELOPMENT CANADA VALCARTIER (QUEBEC), *COMPOSITE STRUCTURES,...
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947
May 28, 2011
05/11
by
Grandhi, Ramana V.; Wang, Lipin
texts
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This report is intended for the demonstration of function approximation concepts and their applicability in reliability analysis and design. Particularly, approximations in the calculation of the safety index, failure probability and structural optimization (modification of design variables) are developed. With this scope in mind, extensive details on probability theory are avoided. Definitions relevant to the stated objectives have been taken from standard text books. The idea of function...
Topics: ACOUSTIC IMPEDANCE, SANDWICH STRUCTURES, FAN BLADES, HIGH FREQUENCIES, AIRCRAFT MODELS, SCALE...
Refinements have been made to a method for estimating the modal sound power levels of a ducted fan ingesting distorted inflow. By assuming that each propagating circumferential mode consists only of a single radial mode (the one with the highest cut-off ratio), circumferential mode sound power levels can be computed for a variety of inflow distortion patterns and operating speeds. Predictions from the refined theory have been compared to data from an experiment conducted in the Advanced Noise...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, AERODYNAMIC NOISE, SOUND PRESSURE, CYLINDRICAL...
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221
Jun 1, 2011
06/11
by
Kogut, A.; Page, L; Spergel, D. N.; Barnes, C.; Bennett, C. L.; Halpern, M.; Hinshaw, G.; Jarosik, N.; Limon, M.; Meyer, S. S.
texts
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The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in Stokes I, Q, and U parameters at frequencies 23, 33, 41, 61, and 94 GHz. We detect correlations between the temperature and polarization maps significant at more than 10 standard deviations. The correlations are inconsistent with instrument noise and are significantly larger than the upper limits established for potential systematic errors. The correlations are present in all WAMP frequency bands with similar amplitude...
Topics: NOISE GENERATORS, AIRCRAFT ENGINES, ENGINE INLETS, FREQUENCIES, MATHEMATICAL MODELS, PREDICTION...
A collection of computer programs has been developed that implements a procedure for predicting multiple-pure-tone (MPT) noise generated by fan blades of an aircraft engine (e.g., a turbofan engine). MPT noise arises when the fan is operating with supersonic relative tip Mach No. Under this flow condition, there is a strong upstream running shock. The strength and position of this shock are very sensitive to blade geometry variations. For a fan where all the blades are identical, the primary...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, COMPUTATIONAL FLUID DYNAMICS, ENGINE...
One source of noise in high tip speed turbofan engines, caused by shocks, is called multiple pure tone noise (MPT's). A new fan, called the Quiet High Speed Fan (QHSF), showed reduced noise over the part speed operating range, which includes MPT's. The QHSF showed improved performance in most respects relative to a baseline fan; however, a partspeed instability discovered during testing reduced the operating range below acceptable limits. The measured QHSF adiabatic efficiency on the fixed...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC CHARACTERISTICS, TURBOFAN ENGINES, FAN BLADES,...
High-temperature polyimide/carbon fiber matrix composites are developed by the Polymers Branch at NASA's Glenn Research Center. These materials can withstand high temperatures and have good processing properties, which make them particularly useful for jet and rocket engines and for components such as fan blades, bushings, and duct segments. Applying polyimide composites as components for aerospace structures can lead to substantial vehicle weight reductions. A typical polyimide composite is...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT STRUCTURES, CARBON FIBERS, TECHNOLOGY ASSESSMENT,...
A major source of noise in commercial turbofan engines is the interaction of the fan blade wakes with the fan exit vanes (stators). These wakes can be greatly reduced by filling them with air blown out of the blade trailing edge. Extensive testing of this concept has demonstrated significant noise reductions. These tests were conducted on a low-speed, 4- ft-diameter fan using hollow blades at NASA Glenn Research Center's Aeroacoustic Propulsion Laboratory (AAPL).
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, TURBOFAN ENGINES, NOISE REDUCTION, AERODYNAMIC...
This report describes a theoretical design and analysis study of the benefits of vane sweep and lean for reducing rotor- stator interaction tone noise. It is shown that the kinematic relationship between the rotor wakes and stator vanes is the principal factor in determining the achievable noise reductions. Vane sweep and lean control rotor wake skewing as seen by the stator vanes and hence influence the number of wake intersections per vane. An increase in the number of intersections reduces...
Topics: NASA Technical Reports Server (NTRS), ACOUSTICS, AERODYNAMIC NOISE, ROTORS, DESIGN ANALYSIS, VANES,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, BROADBAND, FAN BLADES, NOISE GENERATORS,...
There are a variety of innovative new visualization tools available to scientists and engineers for the display and analysis of their models. At the NASA Glenn Research Center, we have an ImmersaDesk, a large, single-panel, semi-immersive display device. This versatile unit can interactively display three-dimensional images in visual stereo. Our challenge is to make this virtual reality platform accessible and useful to researchers. An example of a successful application of this computer...
Topics: NASA Technical Reports Server (NTRS), COMPUTER SYSTEMS DESIGN, DISPLAY DEVICES, VIRTUAL REALITY,...
Many windtunnels use wooden fan blades, however, because of their usual long life (often in excess of 50 years) wooden blades typically do not have to be replaced very often; therefore, the expertise for designing and building wooden windtunnel fan blades is being lost. The purpose of this report is to document the design and build process so that when replacement blades are eventually required some of the critical information required is available. Information useful to fan-blade designers,...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, WOODEN STRUCTURES, WIND TUNNEL APPARATUS, DESIGN,...
A single stage fan and quarter stage booster were designed for the energy efficient engine. The fan has an inlet radius ratio of 0.342 and a specific flow rate of 208.9 Kg/S sq m (42.8 lbm/sec sq ft). The fan rotor has 32 medium aspect ratio (2.597) titanium blades with a partspan shroud at 55% blade height. The design corrected fan tip speed is 411.5 M/S (1350 ft/sec). The quarter stage island splits the total fan flow with approximately 22% of the flow being supercharged by the quarter stage...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC CHARACTERISTICS, AIRCRAFT ENGINES, ENGINE DESIGN,...
Modern fan designs have blades with forward sweep; a lean, thin cross section; and a wide chord to improve performance and reduce noise. These geometric features coupled with the presence of a shock wave can lead to flutter instability. Flutter is a self-excited dynamic instability arising because of fluid-structure interaction, which causes the energy from the surrounding fluid to be extracted by the vibrating structure. An in-flight occurrence of flutter could be catastrophic and is a...
Topics: NASA Technical Reports Server (NTRS), SHOCK WAVES, FLUTTER, FAN BLADES, AEROELASTICITY, WIND TUNNEL...
A combined quadrupole-dipole model of fan inflow distortion tone noise has been extended to calculate tone sound power levels generated by obstructions arranged in circumferentially asymmetric locations upstream of a rotor. Trends in calculated sound power level agreed well with measurements from tests conducted in 2007 in the NASA Glenn Advanced Noise Control Fan. Calculated values of sound power levels radiated upstream were demonstrated to be sensitive to the accuracy of the modeled wakes...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, NOISE PREDICTION, FAN BLADES, QUADRUPOLES,...
Detailed flow measurements between all blade rows were taken in the outer 30 percent of passage height of a two stage fan. Tabulations of the detailed flow measurements are included. Results of these measurements revealed the steep axial velocity profiles near the casing. The axial velocity profile near the casing at the rotor exists was much steeper than at the stator exits. The data also show overturning of the flow at the tip at the stator exits. The effect of mixing is shown by the...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, FLOW MEASUREMENT, TURBINE BLADES, TURBOMACHINERY,...
The fan component which was designed for the energy efficient engine is an advanced high performance, single stage system and is based on technology advancements in aerodynamics and structure mechanics. Two fan components were designed, both meeting the integrated core/low spool engine efficiency goal of 84.5%. The primary configuration, envisioned for a future flight propulsion system, features a shroudless, hollow blade and offers a predicted efficiency of 87.3%. A more conventional blade was...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMICS, CHARACTERISTICS, ENERGY CONSERVATION, ENGINE...
Low Plasticity Burnishing (LPB) has been applied to produce a layer of deep high magnitude compressive residual stress in the leading edge of Ti-6Al-4V first stage fan blades. The goal was to improve damage tolerance from 0.13 to 0.5 mm (0.005 to 0.02 in.). LPB processing of the airfoil surface was performed on a conventional four-axis CNC mill. The LPB control system, tooling, and process are described. A zone of through-thickness compression on the order of 690 MPa (-100 ksi) was achieved...
Topics: DTIC Archive, Prevey, P S, LAMBDA RESEARCH CINCINNATI OH, *FAN BLADES, *TITANIUM ALLOYS, PLASTIC...
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167
Jul 12, 2010
07/10
by
Goodyer, M. J
texts
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Two dimensional airfoil testing in an adaptive wall test-section wind tunnel requires the computation of the imaginary flow fields extending outward from the top and bottom test section walls. A computer program was developed to compute the flow field which would be associated with an arbitrary test section wall shape. The program is based on incompressible flow theory with a Prandtl-Glauert compressibility correction. The program was validated by comparing the streamline and the pressure field...
Topics: FAN BLADES, FLAPS (CONTROL SURFACES), LEADING EDGES, PRESSURE RATIO, THRUST CONTROL, THRUST-WEIGHT...
Impact damage on titanium leading edge configurations was investigated by performing leading edge soft-body impacts on flat-edge and tapered-edge specimens. The objectives were to determine the laboratory specimen size, boundary condition, and test methods necessary to adequately simulate the leading edge local damage of actual blades from soft-body impacts (such as birds). The effects of leading edge geometry, specimen mounting, impact velocity, impactor type, impactor size, and impact angle...
Topics: DTIC Archive, Bertke, Robert S., DAYTON UNIV OH RESEARCH INST, *IMPACT, *DAMAGE, *FAN BLADES,...
257
257
May 30, 2011
05/11
by
Ritzert, F. J.; Yun, H. M.; Miner, R. V
texts
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Single crystal fibers of yttria (Y2O3)-stabilized cubic zirconia, (ZrO2) with ternary oxide additions were grown using the laser float zone fiber processing technique. Ternary additions to the ZrO2-Y2O3 binary system were studied aimed at increasing strength while maintaining the high coefficient of thermal expansion of the binary system. Statistical methods aided in identifying the most promising ternary oxide candidate (Ta2O5, Sc2O3, and HfO2) and optimum composition. The yttria, range...
Topics: ROTOR AERODYNAMICS, COST EFFECTIVENESS, POROSITY, BLADE TIPS, CLEARANCES, AERODYNAMIC NOISE, NOISE...
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261
May 31, 2011
05/11
by
Jorgensen, Charles; Lee, Diana Dee; Agabon, Shan
texts
eye 261
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Sub-vocal electromyogram/electro palatogram (EMG/EPG) signal classification is demonstrated as a method for silent speech recognition. Recorded electrode signals from the larynx and sublingual areas below the jaw are noise filtered and transformed into features using complex dual quad tree wavelet transforms. Feature sets for six sub-vocally pronounced words are trained using a trust region scaled conjugate gradient neural network. Real time signals for previously unseen patterns are classified...
Topics: PROBABILITY DISTRIBUTION FUNCTIONS, RESIDUAL STRENGTH, RELIABILITY ANALYSIS, STRUCTURAL FAILURE,...
Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC PROPERTIES, AERODYNAMIC NOISE, TURBOFANS, NOISE...
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271
Jun 13, 2011
06/11
by
James, Mark A.; Dawicke, David S.; Brzowski, Matthew B.; Raju, Ivatury S.; Elliott, Kenny B.; Harris, Charles E
texts
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Inspections of the Space Shuttle Main Engine revealed fatigue cracks growing from slots in the flow liner of the liquid hydrogen (LH2) feed lines. During flight, the flow liners experience complex loading induced by flow of LH2 and the resonance characteristics of the structure. The flow liners are made of Inconel 718 and had previously not been considered a fracture critical component. However, fatigue failure of a flow liner could have catastrophic effect on the Shuttle engines. A fracture...
Topics: HONEYCOMB CORES, ACOUSTIC VELOCITY, ELECTRICAL IMPEDANCE, BROADBAND, AIRCRAFT ENGINES, LININGS,...
The prediction of fan noise is an important part to the prediction of overall turbofan engine noise. Advances in computers and better understanding of the flow physics have allowed researchers to compute sound generation from first principles and rely less on empirical correlations. While progress has been made, there are still many aspects of the problem that need to be explored. This paper presents some recent advances in fan noise prediction and suggests areas that still need further...
Topics: NASA Technical Reports Server (NTRS), NOISE PREDICTION, AERODYNAMIC NOISE, AEROACOUSTICS, TURBOFAN...
Various new technologies currently under development may enable controlled blade shape variability, or so-called blade morphing, to be practically employed in aircraft engine fans and compressors in the foreseeable future. The current study is a relatively brief, preliminary computational fluid dynamics investigation aimed at partially demonstrating and quantifying the aerodynamic potential of fan rotor blade morphing. The investigation is intended to provide information useful for near-term...
Topics: NASA Technical Reports Server (NTRS), FAN BLADES, ROTOR SPEED, AERODYNAMIC NOISE, PRESSURE RATIO,...
